Adam M. Brufsky, M.D., Ph.D., from the University of Pittsburgh Cancer Institute, and colleagues investigated whether zoledronic acid is effective in maintaining bone health for postmenopausal women with breast cancer receiving adjuvant aromatase inhibitor therapy. A total of 602 women receiving adjuvant letrozole were randomly allocated in a 1:1 ratio to receive upfront or delayed-start zoledronic acid (4 mg intravenously every six months) for five years. The change in lumbar spine (LS) BMD at month 12 was the primary end point.

The investigators found that the adjusted mean difference in LS and total hip BMD between the upfront and delayed-start groups was 8.9 and 6.7 percent, respectively. About 25 percent of patients in the delayed-start group received zoledronic acid by month 61. Grade 4 renal dysfunction was seen in one percent of patients, while there were no confirmed cases of osteonecrosis of the jaw. Fracture rates and Kaplan-Meier disease recurrence rates at month 61 were not significantly different in the upfront and delayed-start groups.

"Upfront adjuvant zoledronic acid significantly increases BMD in postmenopausal early breast cancer patients receiving an aromatase inhibitor for five years, whereas patients randomized to receive delayed zoledronic acid overall progressively lost BMD during the five years," the authors write.

Several authors disclosed financial ties to pharmaceutical companies, including the manufacturer of zolendronic acid, Novartis Pharmaceuticals Corporation, which funded the study.